Dynamical electron correlations in weakly interacting systems: TB-LMTO approach to metals and random alloys

We present a general scheme describing correlation and disorder effects consistently on the same footing in multiband, tight-binding Hamiltonians constructed from linear muffin-tin orbital (LMTO) calculations. The method is applied to determine electronic properties of (disordered) solids with correlated d electrons in the weak-coupling case, $U/w<\mathrm{}1.\mathrm{}$ The correlation part is treated by nonself-consistent dynamical approximations with the chemical potential adjusted so as to preserve the LMTO band filling. The effect of disorder is included via the coherent potential approximation. The calculated density of states for the transition metals gets narrower but it is only little influenced by electron correlations at the Fermi energy. A precursor of a satellite band in paramagnetic fcc Ni is found at about 6 eV below the Fermi level in reasonable quantitative agreement with experiment. The combined effect of electron correlations and of disorder is illustrated on a paramagnetic ${\mathrm{Cu}}_{75}{\mathrm{Ni}}_{25}$ alloy.